(Updates with comments from Elizabeth Warren, background about more recent proposed class action filings and a call by U.S. Senator for the SEC to also investigate)

By Sarah N. Lynch

WASHINGTON, Sept 29 (Reuters) - At least five Wells Fargo employees have sued the bank or filed complaints with regulators alleging that they were fired after reporting the opening of customer accounts without their permission, according to a Reuters review of lawsuits and complaints to the U.S. Labor Department.

The suits and complaints, filed between 2010 and 2014, raise questions about how early Wells Fargo knew about such allegations and how it handled them.

Wells Fargo was ordered to pay $190 million in fines and restitution this month after regulators said its high-pressure sales environment led to the opening of as many as 2 million customer accounts that customers may not have authorized.

Wells Fargo spokeswoman Richele Messick declined to comment on the employees' allegations but said the bank "takes measures to protect team members from retaliation."

One of the fired employees was Birinder Kaur Shankar, a former Colorado-based customer sales representative who in July 2014 filed a complaint with the Labor Department's Occupational Safety and Health Administration (OSHA).

She claimed that the bank retaliated against her after she reported in 2013 that local managers were pressuring employees to engage in "gaming" the bank's sales quotas by opening unauthorized accounts.

In the complaint reviewed by Reuters, Shankar alleged that service managers, branch managers and district managers were "well versed in the art of creative selling" and that customer sales staffers had "direct orders to mislead customers."

"Little did I know that my complaints to the ethics hotline of Wells Fargo Bank on these practices would be openly and directly conveyed to the very managers who would then start collecting write-up data on me," she wrote.

Shankar settled with the bank in 2015 for an undisclosed sum, according to Labor Department records. Shankar declined to comment, citing a confidentiality agreement that was a condition of her settlement.

Another former Wells personal banker, Claudia Ponce de Leon, filed an OSHA complaint in December 2011, alleging that the bank made it "virtually impossible" for branch employees to meet ambitious quotas without cheating.

Ponce de Leon was promoted to become a branch general manager in Pomona, California in June 2011 and discovered employees were engaged in "excessive gaming," according to the complaint.

Shortly after she raised concerns about the practice, she was "terminated without cause," according to her complaint.

Nearly five years later, her attorney Yosef Peretz said she has only received sporadic communications from OSHA and has not been interviewed by investigators. Only recently did OSHA show more interest, he said.

"I heard from them very recently - after this whole mess with Wells Fargo," he said.

The Labor Department has an obligation to efficiently handle such complaints from rank-and-file Wells workers, said Massachusetts Senator Elizabeth Warren, a frequent critic of the banking industry.

"Wells Fargo might want to push the blame for the consequences of its fraudulent actions onto low-level employees, but the Department of Labor should stand up for workers," Warren told Reuters.

Labor Department spokeswoman Amanda McClure did not provide comments in response to questions from Reuters about how OSHA handled the Wells Fargo complaints.

Labor Secretary Thomas Perez told Warren in a Sept. 26 letter that his office now plans a "top-to-bottom" review of all allegations that the department has received concerning Wells Fargo.

Two other clients of Peretz - former personal bankers Yesenia Guitron and Judi Klosek - also filed OSHA complaints, as well as a joint federal lawsuit in 2010 claiming Wells Fargo retaliated against them for blowing the whistle on similar conduct.

Guitron alleged that managers responded by falsifying a paper trail that purported to document her poor performance, forbidding her from taking family medical leave and firing her improperly. Klosek said the bank improperly gave away her position while she was on disability to receive treatment for breast cancer. The bank did not rehire her when she sought other positions, according to her complaint.

A federal judge ultimately dismissed all of Guitron's claims against the bank, saying Wells Fargo was justified for firing her because she failed to meet sales quotas and refused to meet with management.

Guitron said she feels vindicated by the sanctions against Wells Fargo but remains upset that some of the people who she alleges retaliated against her still work at the bank.

"If Wells Fargo wanted to make it right, I would say those people need to go," she said.

The judge dismissed Klosek's retaliation claims but upheld her contention that she was discriminated against based on her disability. She settled with the bank on terms that were not disclosed. Reuters was not able to locate Klosek for comment.

Julie Tishkoff, a former employee who worked as an administrative assistant to a regional bank president, made similar claims in a state lawsuit in 2011. She alleged that she reported "fraudulent banking practices" as far back as November 2005, involving "bank employees forging customer signatures and fraudulently opening accounts."

Tishkoff said the bank "instituted a four-year campaign of retaliation" that included attacking her job performance and public criticism, according to the lawsuit.

Messick, the Wells Fargo spokeswoman, said the bank had settled the case in 2012. Attorneys for Tiskoff did not immediately respond to requests for comment.

After Wells Fargo was ordered to pay penalties and restitution, former employees filed proposed class-action lawsuits claiming they were pressured to meet sales quotas and wrongfully terminated.

On Thursday, Warren, along with Senate Democrats Jeff Merkley of Oregon and Bob Menendez of New Jersey, also separately called on the Securities and Exchange Commission to investigate Wells Fargo for potentially misleading investors and violating whistleblower protection rules. (Reporting by Sarah N. Lynch in Washington Editing by Soyoung Kim and Brian Thevenot)